Update (12/13 9:30am): The WeMo Switch is once again available for $39.99 with free shipping.

Update (12/4 10:13pm): The WeMo Light Switch is now sold out but Amazon has just put the Belkin WeMo Switch on sale for the same $39.99 with free shipping.

The Belkin WeMo Switch lets you turn electronic devices on or off from anywhere inside–or outside–your home. The WeMo Switch uses your existing home Wi-Fi network to provide wireless control of TVs, lamps, stereos, and more. Simply download the free WeMo app, plug the switch into an outlet in your home, and plug any device into the switch. You’ll be able to turn that device on or off using your smartphone or tablet. You can even set schedules for your devices and control them remotely using a mobile Internet connection. You can also add additional switches to your home to control more devices.

Today only, Amazon is offering the Belkin WeMo Light Switch for $39.99 with free shipping. That’s a savings of 20% off retail and the best price we’ve ever seen.

This gadget replaces your current light switch (using the same electrical wiring) and then allows “users to remotely access and manage an entire bank of household lights from anywhere using the WeMo app.” The free app is able to “turn lights on or off, put them on a schedule, and even time them according to local sunrise and sunset.” WeMo Light Switch will work over 3G or WiFi and does not require a monthly subscription. Rated 3.5 out of 5 stars. Check out the entire Belkin WeMO home automation lineup here.

Looking for even deeper home automation? Get the Nest Learning Thermostat (2nd generation) with a FREE $40 Amazon credit voucher for $249.